The roller tappet is an important part of the automobile engine using high-pressure oil pump system, and is mounted between the driving cam and the tappet to transform the rotational motion of the driving cam into the linear reciprocating motion of the tappet. The main structure of the roller tappet includes a shell, a holder, a roller and a pin.
The existing shell of the high pressure oil pump roller tappet is made by integrated forging process, which is complex and costly, and has a certain requirement on the thickness of the plate during stamping. As a result, it is difficult to reduce weight and the cost. The shell may be forged integrally with the holder. Alternatively, the holder may be directly arranged on the shell. As a result, the lateral force acting on the holder from the driving cam will be transmitted to the shell, causing the vibration of the shell inside the cylinder. Accordingly, damages to the cylinder and the shell are likely to be caused. The bottom of the holder is a plane. When the holder vibrates, there will be partial wearing of tappet which contacts the holder. In order to limited to the axial motion of the roller tappet, it is necessary to embed locking blocks in the lateral side of the shell. The locking block is a separate structure from the shell. Its manufacture process is complex.